In general, methylated amines are prepared by the reductive methylation of a suitable amine, for example, diethylenetriamine, using a reductive methylation catalyst, formaldehyde, and hydrogen.
Hitherto, such reactions have been carried out at relatively high pressures, for example, from 50 to 200 bar. For example, DE 25 45 695-A and DE 26 18 580-A (BASF) both disclose reductive methylation processes, carried out at a pressure of 200 bar.
At such relatively high pressures, acceptably high yields can be obtained (for example from 90 to 95 percent) Commercially however, it is disadvantageous to utilize such high pressures, because of the need for relatively complex equipment an handling operations.
Japanese published Patent Application number 60-130551 discloses a low pressure process for the reductive methylation of amines, to produce tertiary amines. However, the process requires an expensive platinum or palladium catalyst.
It is the object of this invention to provide a method for the preparation of permethylated amines avoiding the use of complex high pressure equipment and expensive metal catalysts.